Resin composition and power semiconductor device

Abstract

Provided is a resin composition used for sealing a power semiconductor element in a power semiconductor module to be bonded to a heat dissipation member by sintering. The resin composition contains an epoxy resin, a maleimide compound, and a curing agent.

Description

Resin Composition and Power Semiconductor Device

[0001] The present invention relates to a resin composition and a power semiconductor device.

[0002] A power semiconductor element is a type of semiconductor element mainly used for controlling the voltage or frequency of electric power, converting direct current to alternating current or alternating current to direct current, etc., and is used in various fields powered by electric power such as electronic devices, motors, and power generation devices. In power semiconductor devices, there is a shift from conventional Si devices to SiC devices, and it is expected to increase the operating temperature, rated voltage, etc. Therefore, the general epoxy resin composition used so far lacks heat resistance, and a sealing material that can withstand use at a higher operating temperature, etc., is required. Since power semiconductor elements generate a large amount of heat during use, there is a tendency for the reliability during use to decrease. Therefore, power semiconductor modules including power semiconductor elements are required to have electrical reliability that can withstand use under high voltage and large current conditions. As a resin composition for encapsulating power semiconductor elements, a resin composition containing an epoxy resin is widely used (for example, see Patent Document 1).

[0003] By the way, since a power semiconductor element handles a large current and generates a large amount of heat, it is joined to a heat dissipation member to dissipate heat thereby. Since the heat dissipation member is generally made of metal, an insulating member is provided between the power semiconductor element and the heat dissipation member for insulation. The connection between the insulating member and the heat dissipation member is performed by a heat dissipation paste or solder.

[0004] International Publication No. 2013 / 047696

[0005] In recent years, power semiconductor devices have become larger, and there is a growing need to more efficiently dissipate the heat emitted from power semiconductor elements. From this perspective, attempts are being made to change the bonding between insulating members and heat dissipating members from heat dissipation paste or solder to sintered materials. However, when bonding between insulating members and heat dissipating members is done by sintering, the entire power semiconductor module is heated. As a result, the sealing material that encases the power semiconductor elements is prone to peeling off from the substrate due to sintering. The object of this disclosure is to provide a resin composition capable of forming a sealing portion in which peeling off from the substrate due to sintering is suppressed, and a power semiconductor device manufactured using this resin composition.

[0006] This disclosure includes the following embodiments: <1> A resin composition used for sealing a power semiconductor element in a power semiconductor module that is bonded to a heat dissipation member by sintering, comprising an epoxy resin, a maleimide compound, and a curing agent. <2> The resin composition according to <1>, wherein the content of the maleimide compound is 30% by mass or more relative to the content of the epoxy resin. <3> The resin composition according to <1> or <2>, comprising a sulfur-containing compound. <4> The resin composition according to any one of <1> to <3>, wherein the curing agent comprises a phenol resin. <5> A power semiconductor device comprising a power semiconductor element, an insulating substrate, and a heat dissipation member in this order, wherein the power semiconductor element is sealed with a cured product of the resin composition according to any one of <1> to <4>, and the insulating substrate and the heat dissipation member are bonded by sintering.

[0007] This disclosure provides a resin composition capable of forming a sealing portion that suppresses peeling from the substrate due to sintering, and a power semiconductor device manufactured using this resin composition.

[0008] This is a schematic cross-sectional view showing an example of a power semiconductor device. This is a plan view of an apparatus for evaluating peelability.

[0009] Embodiments of the present disclosure will be described in detail below. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the components (including elemental steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and they do not limit the present disclosure. In numerical ranges indicated using "~" in the present disclosure, the numerical values ​​before and after "~" are included as the minimum and maximum values, respectively. In numerical ranges described in stages in the present disclosure, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Also, in numerical ranges described in the present disclosure, the upper or lower limit of that numerical range may be replaced with the value shown in the example. In the present disclosure, each component may contain multiple types of the corresponding substance. If multiple types of the substance corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple types of substances present in the composition unless otherwise specified. In the present disclosure, each component may contain multiple types of particles. If multiple types of particles corresponding to each component are present in the composition, the particle size of each component refers to the value for a mixture of such multiple types of particles present in the composition, unless otherwise specified. In this disclosure, the term "layer" includes cases where the layer is formed not only over the entire region when the region in which the layer exists is observed, but also where it is formed only on a part of the region.

[0010] <Resin Composition> The resin composition of this disclosure is a resin composition used for encapsulating power semiconductor elements in a power semiconductor module that are bonded to a heat dissipation member by sintering, and contains an epoxy resin, a maleimide compound, and a curing agent. The reason why the above problems are solved with the resin composition having the above configuration is presumed to be as follows.

[0011] As power semiconductor devices become larger, the impact of substrate warping is becoming more significant. Substrate warping occurs due to the difference in thermal expansion coefficients between the substrate and the encapsulation. When the substrate size is small, even if warping occurs due to heating, the absolute value is small. However, when the substrate size increases, as in power semiconductor devices, the impact of warping becomes apparent. Furthermore, when bonding to the heat dissipation member is performed by sintering, the substrate and encapsulation are directly exposed to heating during sintering. The heating during sintering and the subsequent cooling make delamination of the encapsulation from the substrate very likely to occur. From this situation, it has become clear that adding small amounts of other components, such as additives, to the resin composition that constitutes the encapsulation is not sufficient to suppress delamination from the substrate due to sintering.

[0012] Therefore, this disclosure solves the above problem by changing the resin system. Specifically, the resin composition contains a maleimide compound in addition to an epoxy resin. In this resin system, it is expected that, in addition to the reactions between epoxy resins and between maleimide compounds, the epoxy resin and the maleimide compound also react during the curing reaction, resulting in a complex reaction product. This results in a cured product with a high glass transition temperature. Generally, the adhesive strength of the sealing part decreases significantly at high temperatures, but the sealing part made of the cured product of the resin composition of this disclosure, which has a high glass transition temperature, does not lose adhesive strength even at high temperatures. Therefore, it is presumed that the sealing part obtained from the resin composition of this disclosure will have reduced peeling from the substrate even after the sintering process.

[0013] The resin composition of this disclosure may optionally contain curing accelerators, inorganic fillers, coupling agents, ion exchangers, mold release agents, stress relaxants, flame retardants, colorants, etc. From the viewpoint of further suppressing peeling of the cured encapsulated portion from the substrate, the resin composition of this disclosure preferably contains a sulfur-containing compound. The sulfur-containing compound may be contained as an epoxy resin, as a curing agent, or as a coupling agent. The sulfur-containing compound may be used alone or in combination of two or more. The main components constituting the resin composition of this disclosure are described below.

[0014] (Epoxy resin) The type of epoxy resin included in the resin composition is not particularly limited and can be selected from those commonly used in resin compositions for sealing. Specifically, these include: novolac-type epoxy resins (phenol novolac-type epoxy resins, orthocresol novolac-type epoxy resins, etc.) obtained by condensing or co-condensing a novolac resin obtained by condensing or co-condensing a phenolic compound selected from the group consisting of phenol compounds such as phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, and naphthol compounds such as α-naphthol, β-naphthol, and dihydroxynaphthalene, with an aliphatic aldehyde compound such as formaldehyde, acetaldehyde, or propionaldehyde under an acidic catalyst; triphenylmethane-type epoxy resins obtained by condensing or co-condensing a triphenylmethane-type phenolic resin obtained by condensing or co-condensing the above phenolic compound with an aromatic aldehyde compound such as benzaldehyde or salicylaldehyde under an acidic catalyst; and copolymer-type epoxy resins obtained by epoxidizing a novolac resin obtained by co-condensing the above phenolic compound and naphthol compound with an aldehyde compound under an acidic catalyst. Epoxy resins; diphenylmethane type epoxy resins which are diglycidyl ethers of bisphenol A, bisphenol F, etc.; biphenyl type epoxy resins which are diglycidyl ethers of alkyl-substituted or unsubstituted biphenols; stilbene type epoxy resins which are diglycidyl ethers of stilbene-based phenol compounds; sulfur atom-containing epoxy resins such as diglycidyl ethers of bisphenol S, thioether type epoxy resins, and bisphenol sulfide type epoxy resins; epoxy resins which are glycidyl ethers of alcohols such as butanediol, polyethylene glycol, and polypropylene glycol; glycidyl ester type epoxy resins which are glycidyl esters of polycarboxylic acid compounds such as phthalic acid, isophthalic acid, and tetrahydrophthalic acid; glycidylamine type epoxy resins in which the active hydrogen bonded to the nitrogen atom of aniline, diaminodiphenylmethane, isocyanuric acid, etc. is substituted with a glycidyl group; dicyclopentadiene type epoxy resins which are epoxidized from a co-condensation resin of dicyclopentadiene and a phenol compound;Alicyclic epoxy resins such as vinylcyclohexene diepoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and 2-(3,4-epoxy)cyclohexyl-5,5-spiro(3,4-epoxy)cyclohexane-m-dioxane, which have epoxidized olefin bonds within the molecule; paraxylylene-modified epoxy resins, which are glycidyl ethers of paraxylylene-modified phenol resins; metaxylylene-modified epoxy resins, which are glycidyl ethers of metaxylylene-modified phenol resins; terpene-modified epoxy resins, which are glycidyl ethers of terpene-modified phenol resins; and dicyclopentadiene-modified phenol resins, which are glycidyl ethers of dicyclopentadiene-modified phenol resins. Examples of epoxy resins include: cyclopentadiene-modified epoxy resins, which are glycidyl ethers of cyclopentadiene-modified phenolic resins; polycyclic aromatic ring-modified epoxy resins, which are glycidyl ethers of polycyclic aromatic ring-modified phenolic resins; naphthalene-type epoxy resins, which are glycidyl ethers of naphthalene ring-containing phenolic resins; halogenated phenol novolac-type epoxy resins; hydroquinone-type epoxy resins; trimethylolpropane-type epoxy resins; linear aliphatic epoxy resins obtained by oxidizing olefin bonds with peracids such as peracetic acid; and aralkyl-type epoxy resins, which are epoxidized aralkyl-type phenolic resins such as biphenyl aralkyl resins, phenol aralkyl resins, and naphthol aralkyl resins. Furthermore, epoxides of silicone resins and acrylic resins can also be cited as epoxy resins. These epoxy resins may be used individually or in combination of two or more types.

[0015] From the viewpoint of further increasing the glass transition temperature of the sealed portion formed by curing, it is preferable to include a triphenylmethane type epoxy resin. The proportion of the triphenylmethane type epoxy resin to the total amount of epoxy resin is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. Furthermore, from the viewpoint of balancing various properties such as elastic modulus, fluidity, heat resistance, and moldability, the proportion of the triphenylmethane type epoxy resin to the total amount of epoxy resin may be 100% by mass, preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 93% by mass or less.

[0016] From the viewpoint of further suppressing peeling of the cured and formed sealing portion from the substrate, it is preferable to include a sulfur atom-containing epoxy resin. Examples of sulfur atom-containing epoxy resins include thioether-type epoxy resins.

[0017] The proportion of sulfur atom-containing epoxy resin to the total amount of epoxy resin is preferably 5% by mass or more, more preferably 8% by mass or more, and even more preferably 10% by mass or more. Furthermore, from the viewpoint of balancing various properties such as elastic modulus, fluidity, heat resistance, and moldability, the proportion of sulfur atom-containing epoxy resin to the total amount of epoxy resin is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less.

[0018] The epoxy equivalent (molecular weight / number of epoxy groups) of the epoxy resin is not particularly limited. From the viewpoint of balancing various properties such as elastic modulus, fluidity, heat resistance, and moldability, it is preferably 100 g / eq to 1000 g / eq, and more preferably 150 g / eq to 500 g / eq. The epoxy equivalent of the epoxy resin shall be the value measured by the method in accordance with JIS K 7236:2009.

[0019] When the epoxy resin is solid, its softening point or melting point is not particularly limited. From the viewpoint of moldability and reflow resistance, it is preferably 40°C to 180°C, and from the viewpoint of ease of handling during the preparation of the resin composition, it is more preferably 50°C to 130°C. The melting point of the epoxy resin shall be the value measured by differential scanning calorimetry (DSC), and the softening point of the epoxy resin shall be the value measured by the method (ring-ball method) in accordance with JIS K 7234:1986.

[0020] The epoxy resin content in the resin composition is preferably 0.5% to 50% by mass, and more preferably 2% to 30% by mass, from the viewpoint of elastic modulus, fluidity, heat resistance, moldability, etc.

[0021] (Maleimide Compounds) Maleimide compounds may include compounds having one or more maleimide groups in their molecules, and include compounds having one maleimide group in their molecules and compounds having two or more maleimide groups in their molecules, with it being preferable to include compounds having two or more maleimide groups in one molecule. Maleimide compounds may also include amine compounds as synthesis raw materials. Maleimide compounds may be used individually or in combination of two or more.

[0022] Compounds having one maleimide group in the molecule include N-phenylmaleimide, N-ethylmaleimide, and N-cyclohexylmaleimide. Compounds having two or more maleimide groups in the molecule include 4,4'-diphenylmethanedimaleimide (CAS: 13676-54-5), N,N'-1,3-phenylenedimaleimide (CAS: 3006-93-7), 2,2'-bis[4-(4-maleimoidphenoxy)phenyl]propane (CAS: 79922-55-7), and 3,3'-dimethyl-5,5'- Examples include diethyl-4,4'-diphenylmethanebismaleimide (CAS: 105391-33-1), 4-methyl-1,3-phenylenebismaleimide (CAS: 6422-83-9), 1,6-bismaleimide-(2,2,4-trimethyl)hexane (CAS: 39979-46-9), and polyphenylmethanemaleimide (CAS: 67784-74-1).

[0023] From the viewpoint of further increasing the glass transition temperature of the cured and formed sealing portion and further suppressing peeling of the sealing portion from the substrate, it is preferable to include an aromatic maleimide compound, more preferably an aromatic maleimide compound having two or more maleimide groups in one molecule, and even more preferably an aromatic maleimide compound represented by the following formula (I).

[0024]

[0025] In formula (I), n represents an integer of 0 or greater. The aromatic maleimide compounds represented by formula (I) may be used individually or in combination of two or more.

[0026] From the viewpoint of curability, bismaleimide compounds are preferred. Among these, aromatic bismaleimide compounds such as 4,4'-diphenylmethanedimaleimide (CAS: 13676-54-5, the compound in formula (I) where n is 0), N,N'-1,3-phenylenedimaleimide (CAS: 3006-93-7), 4-methyl-1,3-phenylenebismaleimide (CAS: 6422-83-9), and polyphenylmethanemaleimide (CAS: 67784-74-1) are more preferred from the viewpoint of obtaining a cured product with a high glass transition temperature. From the viewpoint of long-term heat resistance, 2,2'-bis[4-(4-maleimidephenoxy)phenyl]propane (CAS: 79922-55-7) is more preferred, and from the viewpoint of fluidity, 1,6-bismaleimide-(2,2,4-trimethyl)hexane (CAS: 39979-46-9) is more preferred.

[0027] From the viewpoint of further suppressing peeling of the cured and formed sealing portion from the substrate, the content of the maleimide compound is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 45% by mass or more, relative to the content of the epoxy resin. Furthermore, the content of the maleimide compound is preferably 200% by mass or less, more preferably 180% by mass or less, and even more preferably 150% by mass or less, relative to the content of the epoxy resin.

[0028] (Curing agent) The resin composition contains a curing agent. The type of curing agent is not particularly limited and examples include phenol curing agents, amine curing agents, acid anhydride curing agents, polymercaptan curing agents, polyaminoamide curing agents, isocyanate curing agents, and blocked isocyanate curing agents. From the viewpoint of further suppressing peeling of the sealed portion formed by curing from the substrate, it is preferable that the curing agent contains one that has two or more phenolic hydroxyl groups in one molecule (phenol curing agent). The phenolic hydroxyl groups of the phenol curing agent tend to accelerate the curing reaction of the maleimide compound.

[0029] Specifically, the phenolic curing agents include polyhydric phenolic compounds such as resorcinol, catechol, bisphenol A, bisphenol F, and substituted or unsubstituted biphenols; novolac-type phenolic resins obtained by condensing or co-condensing at least one phenolic compound selected from the group consisting of phenolic compounds such as phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, phenylphenol, aminophenol, and naphthol compounds such as α-naphthol, β-naphthol, and dihydroxynaphthalene, with aldehyde compounds such as formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde under an acidic catalyst; and synthesis from the above phenolic compounds with dimethoxyp-xylene, bis(methoxymethyl)biphenyl, etc. Examples of phenol curing agents include aralkyl-type phenolic resins such as phenol aralkyl resins and naphthol aralkyl resins, and biphenyl aralkyl-type phenolic resins; phenolic resins modified with paraxylylene or metaxylylene; melamine-modified phenolic resins; terpene-modified phenolic resins; dicyclopentadiene-type phenolic resins and dicyclopentadiene-type naphthol resins synthesized by copolymerization of the above phenolic compound and dicyclopentadiene; cyclopentadiene-modified phenolic resins; polycyclic aromatic ring-modified phenolic resins; biphenyl-type phenolic resins; triphenylmethane-type phenolic resins obtained by condensation or co-condensation of the above phenolic compound and aromatic aldehyde compounds such as benzaldehyde and salicylaldehyde under an acidic catalyst; and phenolic resins obtained by copolymerizing two or more of these. These phenol curing agents may be used individually or in combination of two or more.

[0030] From the viewpoint of further suppressing peeling of the cured and formed sealing portion from the substrate, the phenol curing agent is preferably having a triazine skeleton. Examples of phenol curing agents having a triazine skeleton include the phenol curing agent represented by the following formula (1) and the phenol curing agent represented by the following formula (2).

[0031]

[0032]

[0033] In formula (2), p or q is an integer in the range of 1 to 100, preferably an integer in the range of 1 to 50.

[0034] The proportion of the phenol curing agent having a triazine skeleton to the total amount of curing agent is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. Furthermore, from the viewpoint of balancing various properties such as elastic modulus, fluidity, heat resistance, and moldability, the proportion of the phenol curing agent having a triazine skeleton to the total amount of curing agent is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0035] From the viewpoint of suppressing a decrease in the glass transition temperature of the cured product, it is preferable that the phenol curing agent contains a novolac-type phenol curing agent. The proportion of the novolac-type phenol curing agent to the total amount of curing agent is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. Furthermore, from the viewpoint of balancing various properties such as elastic modulus, fluidity, heat resistance, and moldability, the proportion of the novolac-type phenol curing agent to the total amount of curing agent is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less.

[0036] The functional group equivalent of the curing agent (hydroxyl group equivalent in the case of a phenol curing agent) is not particularly limited. From the viewpoint of balancing various properties such as moldability, reflow resistance, and electrical reliability, it is preferably 70 g / eq to 1000 g / eq, and more preferably 80 g / eq to 500 g / eq. The functional group equivalent of the curing agent (hydroxyl group equivalent in the case of a phenol curing agent) shall be the value measured by the method in accordance with JIS K 0070:1992.

[0037] If the curing agent is solid, its softening point or melting point is not particularly limited. From the viewpoint of moldability and reflow resistance, it is preferably 40°C to 180°C, and from the viewpoint of handling during the manufacture of the resin composition, it is more preferably 50°C to 130°C. The melting point or softening point of the curing agent shall be a value measured in the same manner as the melting point or softening point of the epoxy resin.

[0038] The mixing ratio of epoxy resin to curing agent is not particularly limited. From the viewpoint of minimizing unreacted components, it is preferable that the ratio of the number of functional groups of the curing agent to the number of epoxy groups of the epoxy resin (number of epoxy groups of epoxy resin / number of functional groups of curing agent) be set in the range of 0.5 to 2.0, more preferably in the range of 0.6 to 1.3, and even more preferably in the range of 0.8 to 1.2.

[0039] (Curing accelerator) The resin composition may contain a curing accelerator. The type of curing accelerator is not particularly limited and can be selected according to the type of epoxy resin, the desired properties of the resin composition, etc. Examples of curing accelerators include diazabicycloalkenes such as 1,5-diazabicyclo[4.3.0]nonene-5 (DBN) and 1,8-diazabicyclo[5.4.0]undecene-7 (DBU), cyclic amidine compounds such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 2-heptadecylimidazole; derivatives of the cyclic amidine compounds; phenol novolac salts of the cyclic amidine compounds or their derivatives; and quinone compounds such as maleic anhydride, 1,4-benzoquinone, 2,5-toluquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2,6-dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, and phenyl-1,4-benzoquinone. Compounds having intramolecular polarization obtained by adding compounds with π bonds, such as zophenylmethane; cyclic amidinium compounds such as tetraphenylborate salt of DBU, tetraphenylborate salt of DBN, tetraphenylborate salt of 2-ethyl-4-methylimidazole, and tetraphenylborate salt of N-methylmorpholine; tertiary amine compounds such as pyridine, triethylamine, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; derivatives of the above tertiary amine compounds; ammonium salt compounds such as tetra-n-butylammonium acetate, tetra-n-butylammonium phosphate, tetraethylammonium acetate, tetra-n-hexylammonium benzoate, and tetrapropylammonium hydroxide;Triphenylphosphine, tributylphosphine, diphenyl(p-tolyl)phosphine, tris(alkylphenyl)phosphine, tris(alkoxyphenyl)phosphine, tris(alkyl-alkoxyphenyl)phosphine, tris(dialkylphenyl)phosphine, tris(trialkylphenyl)phosphine, tris(tetraalkylphenyl)phosphine, tris(dialkoxyphenyl)phosphine, tris(trialkoxyphenyl)phosphine, tris(tetraalkoxyphenyl)phosphine, tris(tetraalkoxyphenyl)phosphine, and other trialkylphosphines Tertiary phosphines such as phosphates, dialkylarylphosphines, and alkyldiarylphosphines; phosphine compounds such as complexes of the tertiary phosphines with organoborons; quinone compounds such as maleic anhydride, 1,4-benzoquinone, 2,5-tholquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2,6-dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, phenyl-1,4-benzoquinone, and diazophenylmethyl Compounds having intramolecular polarization obtained by adding compounds having π bonds, such as tang; the tertiary phosphine or the phosphine compound and 4-bromophenol, 3-bromophenol, 2-bromophenol, 4-chlorophenol, 3-chlorophenol, 2-chlorophenol, 4-iodidephenol, 3-iodidephenol, 2-iodidephenol, 4-bromo-2-methylphenol, 4-bromo-3-methylphenol, 4-bromo-2,6-dimethylphenol, 4-bromo-3,5-dimethylphenol, 4-bromo-2,6-di-ter Compounds with intramolecular polarization obtained by reacting halogenated phenol compounds such as t-butylphenol, 4-chloro-1-naphthol, 1-bromo-2-naphthol, 6-bromo-2-naphthol, and 4-bromo-4'-hydroxybiphenyl, followed by a dehalogenation step; tetrasubstituted phosphoniums such as tetraphenylphosphonium, tetrasubstituted phosphoniums and tetrasubstituted borates without phenyl groups bonded to the boron atom such as tetra-p-tolylborate; and salts of tetraphenylphosphonium and phenol compounds.

[0040] When the resin composition contains a curing accelerator, the amount thereof is preferably 0.1 part by mass to 30 parts by mass, more preferably 1 part by mass to 15 parts by mass, based on 100 parts by mass of the resin components (the total of the epoxy resin, maleimide compound and curing agent; the same applies hereinafter). When the amount of the curing accelerator is 0.1 part by mass or more based on 100 parts by mass of the resin components, it tends to cure well in a short time. When the amount of the curing accelerator is 30 parts by mass or less based on 100 parts by mass of the resin components, the curing rate is not too fast and a good molded product tends to be obtained.

[0041] (Inorganic filler) The resin composition may contain an inorganic filler. The type of the inorganic filler is not particularly limited and can be selected from those generally used in resin compositions. Specifically, inorganic materials such as fused silica, crystalline silica, glass, alumina, calcium carbonate, zirconium silicate, calcium silicate, silicon nitride, aluminum nitride, boron nitride, beryllia, zirconia, zircon, fosterite, steatite, spinel, mullite, titania, talc, clay, mica, etc. can be mentioned. An inorganic filler having a flame retardant effect may be used. Examples of the inorganic filler having a flame retardant effect include composite metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and composite hydroxide of magnesium and zinc, and zinc borate.

[0042] Among the inorganic fillers, silica such as fused silica is preferable from the viewpoint of reducing the linear expansion coefficient, and alumina is preferable from the viewpoint of high thermal conductivity. The inorganic filler may be used alone or in combination of two or more.

[0043] The content of the inorganic filler in the resin composition is not particularly limited. From the viewpoints of fluidity and strength, the content of the inorganic filler is preferably 30% by volume to 90% by volume, more preferably 50% by volume to 85% by volume, of the whole resin composition. When the content of the inorganic filler is 30% by volume or more of the whole resin composition, the properties such as the thermal expansion coefficient, thermal conductivity, and elastic modulus of the cured product tend to be more improved. When the content of the inorganic filler is 90% by volume or less of the whole resin composition, the increase in the viscosity of the resin composition is suppressed, and the fluidity is more improved and the moldability tends to be better.

[0044] Furthermore, from the viewpoint of fluidity and strength, the inorganic filler content is preferably 70% to 90% by mass of the total resin composition, and more preferably 75% to 90% by mass. When the inorganic filler content is 70% by mass or more of the total resin composition, the properties of the cured product, such as the coefficient of thermal expansion, thermal conductivity, and elastic modulus, tend to improve further. When the inorganic filler content is 90% by mass or less of the total resin composition, the increase in viscosity of the resin composition is suppressed, fluidity improves further, and moldability tends to be better.

[0045] When the inorganic filler is in particulate form, its average particle size is not particularly limited. For example, the overall volume-average particle size of the inorganic filler is preferably 0.2 μm to 10 μm, and more preferably 0.5 μm to 5 μm. When the volume-average particle size is 0.2 μm or more, the increase in viscosity of the resin composition tends to be further suppressed. When the volume-average particle size is 10 μm or less, the ability to fill narrow gaps tends to be further improved. The volume-average particle size of the inorganic filler can be measured as the volume-average particle size (D50) using a laser scattering diffraction particle size distribution analyzer.

[0046] (Coupling agent) The resin composition may contain a coupling agent. Examples of known coupling agents include silane compounds such as epoxysilane, mercaptosilane, aminosilane, alkylsilane, ureidosilane, and vinylsilane, as well as titanium compounds, aluminum chelate compounds, and aluminum / zirconium compounds.

[0047] From the viewpoint of further suppressing peeling of the cured and formed sealing portion from the substrate, it is preferable to include a sulfur-containing coupling agent. Examples of sulfur-containing coupling agents include coupling agents having a mercapto group and coupling agents having a sulfide group, specifically, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, tetrasulfideditriethoxysilane, and the like.

[0048] When the coupling agent includes a sulfur-containing coupling agent, the amount of the sulfur-containing coupling agent is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, relative to the total amount of the coupling agent. Furthermore, when the coupling agent includes a sulfur-containing coupling agent, from the viewpoint of balancing various properties such as elastic modulus and moldability, the amount of the sulfur-containing coupling agent is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less, relative to the total amount of the coupling agent.

[0049] From the viewpoint of increasing the strength of the sealed portion formed by curing, the coupling agent is preferably a benzene ring-containing coupling agent. The amount of the benzene ring-containing coupling agent is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, based on the total amount of the coupling agent. Furthermore, when the coupling agent contains a benzene ring-containing coupling agent, from the viewpoint of balancing various properties, the amount of the benzene ring-containing coupling agent is preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less, based on the total amount of the coupling agent.

[0050] If the resin composition contains a coupling agent, the amount of the coupling agent is preferably 0.05 to 5 parts by mass, and more preferably 0.1 to 2.5 parts by mass, per 100 parts by mass of the inorganic filler.

[0051] (Release Agent) The resin composition may contain a release agent from the viewpoint of obtaining good release properties from the mold during molding. The release agent is not particularly limited, and conventionally known ones can be used. Specifically, examples include carnauba wax, higher fatty acids such as montanic acid and stearic acid, higher fatty acid metal salts, ester waxes such as montanic acid esters, and polyolefin waxes such as oxidized polyethylene and non-oxidized polyethylene. The release agent may be used alone or in combination of two or more types.

[0052] If the resin composition contains a release agent, the amount is preferably 0.01 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the resin component. When the amount of release agent is 0.01 parts by mass or more per 100 parts by mass of the resin component, sufficient release properties tend to be obtained. When it is 10 parts by mass or less, better adhesion tends to be obtained.

[0053] (Colorants) The resin composition may further contain colorants. Examples of known colorants include carbon black, organic dyes, organic pigments, titanium dioxide, red lead, and red iron oxide. The amount of colorant can be appropriately selected depending on the purpose. One colorant may be used alone, or two or more colorants may be used in combination.

[0054] (Stress Relief Agent) The resin composition may contain stress relief agents such as silicone oil and silicone rubber particles. Including stress relief agents can further reduce package warping deformation and package cracking. Examples of stress relief agents include commonly used and known stress relief agents (flexible agents). Specifically, these include thermoplastic elastomers such as silicone-based, styrene-based, olefin-based, urethane-based, polyester-based, polyether-based, polyamide-based, and polybutadiene-based; rubber particles such as NR (natural rubber), NBR (acrylonitrile-butadiene rubber), acrylic rubber, urethane rubber, and silicone powder; and rubber particles having a core-shell structure such as methyl methacrylate-styrene-butadiene copolymer (MBS), methyl methacrylate-silicone copolymer, and methyl methacrylate-butyl acrylate copolymer. One type of stress relief agent may be used alone, or two or more types may be used in combination.

[0055] (Ion Exchanger) The resin composition may contain an ion exchanger. In particular, it is preferable to include an ion exchanger from the viewpoint of improving the moisture resistance and high-temperature storage characteristics of electronic component devices equipped with sealed elements. The ion exchanger is not particularly limited, and conventionally known ones can be used. Specifically, examples include hydrotalcite compounds and hydrated oxides of at least one element selected from the group consisting of magnesium, aluminum, titanium, zirconium, and bismuth. The ion exchanger may be used alone or in combination of two or more. Among these, hydrotalcite represented by the following general formula (A) is preferred.

[0056] Mg （１－Ｘ） Al Ｘ (OH) ２ (CO ３ ) Ｘ／２ mH ２ O ……(A) (0 < X ​​≤ 0.5, m is a positive number)

[0057] If the resin composition contains an ion exchanger, there are no particular restrictions on its content as long as it is sufficient to capture ions such as halogen ions. For example, it is preferably 0.1 to 30 parts by mass, and more preferably 1 to 5 parts by mass, per 100 parts by mass of the resin component.

[0058] (Flame retardant) The resin composition may contain a flame retardant. The flame retardant is not particularly limited, and conventionally known ones can be used. Specifically, examples include organic or inorganic compounds containing halogen atoms, antimony atoms, nitrogen atoms, or phosphorus atoms, metal hydroxides, etc. The flame retardant may be used alone or in combination of two or more types.

[0059] If the resin composition contains a flame retardant, the amount is not particularly limited as long as it is sufficient to obtain the desired flame retardant effect. For example, it is preferably 1 to 30 parts by mass, and more preferably 2 to 15 parts by mass, per 100 parts by mass of the resin component.

[0060] <Method for preparing the resin composition> The method for preparing the resin composition is not particularly limited. A common method is to thoroughly mix predetermined amounts of components using a mixer or the like, then melt-knead them using a mixing roll, extruder or the like, cool them, and pulverize them. More specifically, for example, a method can be used in which predetermined amounts of the above-mentioned components are uniformly stirred and mixed, then kneaded using a kneader, roll, extruder or the like that has been preheated to 70°C to 140°C, then cooled, and pulverized.

[0061] The resin composition is preferably solid at room temperature and atmospheric pressure (for example, 25°C and atmospheric pressure). The shape of the resin composition when it is solid is not particularly limited and may be in the form of powder, granules, tablets, etc.

[0062] <Physical Properties> (Glass Transition Temperature) The glass transition temperature of the cured resin composition is preferably 180°C or higher, more preferably 190°C or higher, and even more preferably 200°C or higher. A higher glass transition temperature of the cured product is desirable.

[0063] The glass transition temperature of a cured resin composition is determined by performing dynamic viscoelasticity measurements in tensile mode. The temperature at which tanδ is maximized in the relationship diagram between the obtained temperature and tanδ is defined as the glass transition temperature.

[0064] (Coefficient of linear expansion) The coefficient of linear expansion (CTE1) of the cured resin composition at temperatures below the glass transition temperature is preferably 23 ppm / °C or less, more preferably 20 ppm / °C or less, and even more preferably 16 ppm / °C or less. Furthermore, the CTE1 of the cured resin composition is preferably 5 ppm / °C or more, more preferably 6 ppm / °C or more, and even more preferably 8 ppm / °C or more.

[0065] The coefficient of linear expansion (CTE2) of the cured resin composition at temperatures above the glass transition temperature is preferably 100 ppm / °C or less, more preferably 90 ppm / °C or less, and even more preferably 80 ppm / °C or less. Furthermore, the CTE2 of the cured resin composition is preferably 30 ppm / °C or more, more preferably 40 ppm / °C or more, and even more preferably 50 ppm / °C or more.

[0066] The coefficient of linear expansion of the cured resin composition is determined by thermomechanical analysis in accordance with JIS K 7197:2012, as the slope of the tangent line to a graph plotting the strain of the cured material against temperature. CTE1 is determined as the slope of the tangent line in the range of 10°C to 30°C, and CTE2 is determined as the slope of the tangent line in the range of 220°C to 260°C.

[0067] (Measurement of flexural strength) The cured resin composition preferably has a flexural strength of 70 MPa or more at 25°C, more preferably 80 MPa or more, and even more preferably 90 MPa or more. There is no particular upper limit to the flexural strength at 25°C.

[0068] The cured resin composition preferably has a flexural strength of 10 MPa or more at 260°C, more preferably 12 MPa or more, and even more preferably 15 MPa or more. There is no particular upper limit to the flexural strength at 260°C.

[0069] The flexural strength of the cured resin composition is determined by performing flexural tests at 25°C and 260°C using a Tensilon universal material testing machine. A flexural stress-displacement curve is created from equation (A), and the maximum stress is defined as the flexural strength (MPa).

[0070] σ = 3FL / 2bh ２ ...Formula (A) σ: Bending stress (MPa) F: Bending load (N) L: Distance between supports (mm) b: Specimen width (mm) h: Specimen thickness (mm)

[0071] (Flexural Modulus) The cured resin composition preferably has a flexural modulus of 25 GPa or less at 25°C, more preferably 20 GPa or less, and even more preferably 15 GPa or less. There is no particular lower limit to the flexural modulus at 25°C.

[0072] The cured resin composition preferably has a flexural modulus of 6.0 GPa or less, more preferably 4.5 GPa or less, even more preferably 3.0 GPa or less, particularly preferably 2.5 GPa or less, and most preferably 2.0 GPa or less. There is no particular lower limit to the flexural modulus of 260°C.

[0073] The flexural modulus of the cured resin composition is determined by preparing test specimens according to JIS K7171:2016 and performing a three-point bending test.

[0074] (Hardness when hot) The cured product of the resin composition preferably has a hardness when hot of 70 or higher, more preferably 75 or higher, and even more preferably 80 or higher. There is no particular upper limit to the hardness when hot.

[0075] The thermal hardness of the cured resin composition is measured using a Shore hardness tester type D.

[0076] (Shear Adhesion) The cured resin composition preferably has a shear adhesion strength to copper at 25°C of 3 MPa or more, more preferably 4 MPa or more, and even more preferably 6 MPa or more. There is no particular upper limit to the shear adhesion strength to copper at 25°C.

[0077] The cured resin composition preferably has a shear adhesion strength to copper at 260°C of 0.5 MPa or more, more preferably 0.8 MPa or more, and even more preferably 1.0 MPa or more. There is no particular upper limit to the shear adhesion strength to copper at 260°C.

[0078] The cured resin composition preferably has a shear adhesion strength to silver at 25°C of 3 MPa or more, more preferably 4 MPa or more, and even more preferably 6 MPa or more. There is no particular upper limit to the shear adhesion strength to silver at 25°C.

[0079] The cured resin composition preferably has a shear adhesion strength to silver at 260°C of 0.5 MPa or more, more preferably 0.8 MPa or more, and even more preferably 1.0 MPa or more. There is no particular upper limit to the shear adhesion strength to silver at 260°C.

[0080] The shear adhesion strength of the cured resin composition is measured using a bond tester at a shear rate of 50 μm / s.

[0081] (Uses of the resin composition) The resin composition of this disclosure is used for sealing power semiconductor elements in power semiconductor modules that are bonded to a heat dissipation member by sintering. However, since the resin composition of this disclosure prevents delamination from the substrate, it may also be used for purposes other than this.

[0082] <Power Semiconductor Device> The power semiconductor device of the present disclosure comprises, in this order, a power semiconductor element, an insulating substrate, and a heat dissipation member, wherein the power semiconductor element is sealed with a cured product of the resin composition of the present disclosure, and the insulating substrate and the heat dissipation member are bonded together by sintering.

[0083] Common power semiconductor elements can be used. Insulating substrates can be common ones used in power semiconductor devices. For example, insulating substrates can be ceramic substrates such as alumina, aluminum nitride, or silicon nitride. Heat dissipation members may be heat sinks, heat spreaders, or cooling members. Heat dissipation members may be made of metals such as aluminum or copper. For sintering, for example, silver sintering or copper sintering can be used, from the viewpoint of thermal conductivity.

[0084] Figure 1 is a schematic cross-sectional view showing an example of a power semiconductor device. Specific examples of power semiconductor devices will be described with reference to Figure 1, but this disclosure is not limited thereto. Furthermore, the sizes of the components in Figure 1 are conceptual, and the relative relationships between the components are not limited thereto.

[0085] The power semiconductor elements 2 are arranged on a substrate 4 made of copper or the like, and the chips including these are connected by wires 6. The wires 6 may be replaced with other conductive members such as busbars. An insulating layer 10 is placed on the side of the substrate 4 opposite to the power semiconductor elements 2, and another substrate 12 made of copper or the like is provided on the other side of the insulating layer 10. The power semiconductor module including these is sealed as a whole with a sealing material to form a sealing portion 14. Methods for forming the sealing portion 14 include the transfer molding method and the compression molding method. The substrate 12 is bonded to a heat dissipation member 16 by sintering, and a bonding portion 18 is formed between them.

[0086] Furthermore, since the power semiconductor element 2 and the substrate 4 are bonded before the sealing portion 14 is formed, it is not necessary to consider the effect on the sealing portion 14 when forming the bonding portion 8. For this reason, the bonding portion 8 may be bonded by sintering or by soldering.

[0087] The present disclosure will be described in detail below with reference to examples, but the scope of the present disclosure is not limited to these examples.

[0088] (Preparation of Resin Composition) The components shown below were blended in the proportions (parts by mass) shown in Table 1, and roll kneading was performed at a kneading temperature of 80°C for a kneading time of 10 minutes to prepare the resin composition.

[0089]

[0090] Details of each component shown in the table are as follows: • Epoxy resin A: Triphenylmethane type epoxy resin (epoxy equivalent: 169 g / eq) • Epoxy resin B: Biphenyl type epoxy resin (epoxy equivalent: 195 g / eq) • Epoxy resin C: Thioether type epoxy resin (epoxy equivalent: 244 g / eq) • Maleimide compound: 4,4'-diphenylmethanedimaleimide • Curing agent A: Biphenyl aralkyl type phenol resin (hydroxyl equivalent: 199 g / eq) • Curing agent B: Phenol novolac resin with a triazine skeleton (hydroxyl equivalent: 120 g / eq) • Curing agent C: Triphenylmethane type phenol resin (hydroxyl equivalent: 104 g / eq) • Curing agent D: Phenol novolac resin (hydroxyl equivalent: 103 g / eq) • Curing agent E: Monofunctional phenol compound with a triazine skeleton (molecular weight 509.6) • Curing accelerator A: Addition product of triphenylphosphine and 1,4-benzoquinone • Curing accelerator B: Addition product of tributylphosphine and 1,4-benzoquinone • Curing accelerator C: 2-phenyl-4-methylimidazole • Coupling agent A: 3-glycidyloxypropyltrimethoxysilane • Coupling agent B: 3-methacryloxypropyltrimethoxysilane • Coupling agent C: Tetrasulfide ditriethoxysilane • Coupling agent D: N-phenyl-3-aminopropyltrimethoxysilane • Release agent: Oxidized polyethylene wax • Coloring agent: Carbon black • Stress reliever A: Silicone-based core-shell rubber particles • Stress reliever B: Silicone resin • Other additive A: Hydrotalcite • Other additive B: Gallic acid • Inorganic filler A: Spherical fused silica (volume average particle size: 18.8 μm) • Inorganic filler B: Spherical fused silica (volume average particle size: 0.5 μm)

[0091] (Preparation of cured specimens for measurement) Cured specimens for measuring glass transition temperature, linear expansion coefficient, flexural strength, flexural modulus, and hot hardness were obtained as follows: The resin composition was molded in a transfer molding machine under the conditions of a mold temperature of 175°C, a molding pressure of 6.9 MPa, and a curing time of 120 seconds. Subsequently, the molded material was post-cured at 175°C for 5 hours to obtain a cured specimen. For each measurement, a specific shape was cut from the cured specimen to serve as the test specimen.

[0092] (Measurement of Glass Transition Temperature) The cured material was cut into strips measuring 2 mm × 0.5 mm × 40 mm to prepare test specimens for evaluating the glass transition temperature. The glass transition temperature of the test specimens was calculated by performing dynamic viscoelasticity measurements in tensile mode. The measurement conditions were a frequency of 10 Hz, a heating rate of 5 °C / min, and a strain of 0.1%. In the relationship diagram between the obtained temperature and tanδ, the temperature at which tanδ was maximum was considered to be the glass transition temperature. An RSA-G2 (TA Instruments Corporation) was used as the evaluation device. The results are shown in Table 2.

[0093] (Measurement of Linear Expansion Coefficient) A specimen for evaluating the linear expansion coefficient was prepared by cutting the cured material to a size of 5.1 mm on the short side, 20 mm on the long side, and 2 mm in thickness. Then, using thermomechanical analysis based on JIS K 7197:2012, the slope of the tangent line when the strain of the cured material was plotted against temperature was determined in the ranges of 10°C to 30°C and 220°C to 260°C. The slope of the tangent line in the range of 10°C to 30°C is shown as CTE1, and the slope of the tangent line in the range of 220°C to 260°C is shown as CTE2 in Table 2. The test load was 5 g and the heating rate was 5°C / min. A TMA high-precision two-sample thermal analyzer (instrument name SS6100) manufactured by Seiko Instruments Inc. was used to measure the linear expansion coefficient.

[0094] (Measurement of Bending Strength) The hardened material was cut into pieces measuring 4.0 mm × 10.0 mm × 80 mm to prepare test specimens for evaluating bending strength. The obtained test specimens were subjected to bending tests at 25°C and 260°C using a Tensilon universal material testing machine (Instron 5948, Instron Corporation) under the conditions of a support distance of 64 mm, a crosshead speed of 10 mm / min, and a temperature of 25°C. Using the measured results, a bending stress-displacement curve was created from the above formula (A), and the maximum stress was defined as the bending strength (MPa). The results are shown in Table 2.

[0095] (Measurement of flexural modulus) Test specimens were prepared according to JIS K7171 (2016), and the flexural modulus (GPa) at 25°C and 260°C was determined by three-point bending measurement. A Tensilon (A&D Company, Limited) evaluation device was used. The results are shown in Table 2.

[0096] (Measurement of thermal hardness) The hardened material was cut into pieces measuring 4 mm x 80 mm x 10 mm to prepare test specimens for measuring thermal hardness. The thermal hardness of the obtained test specimens was measured using a Shore hardness tester type D (manufactured by Polymer Instruments Co., Ltd.). The results are shown in Table 2.

[0097] (Measurement of shear adhesion strength) The resin composition was molded onto a copper or silver plate using a transfer molding machine under the following conditions: mold temperature 175°C, molding pressure 6.9 MPa, and curing time 120 seconds, to a size of 4 mm in base diameter, 3 mm in top diameter, and 4 mm in height. Subsequently, the molded product was post-cured at 175°C for 5 hours to obtain test specimens for adhesion strength measurement. The shear adhesion strength (MPa) of the obtained test specimens was determined using a bond tester (Nordson Advanced Technologies, Inc., Series 4000) at room temperature (25°C) or while maintaining the temperature of the copper or silver plate at 260°C, at a shear rate of 50 μm / s. The results are shown in Table 2.

[0098] (Evaluation of Peelability) <Preparation of Evaluation Device> An evaluation device as shown in Figure 2 was prepared. Figure 2 is a plan view of the peelability evaluation device. As an insulating heat dissipation circuit board, a silicon nitride plate 10 measuring 40.0 mm × 40.0 mm × 0.32 mm thick was used, to which a copper plate 12 measuring 38.5 mm × 38.5 mm × 0.92 mm thick was bonded. Cu leads (not shown) were bonded to two opposing sides of the insulating heat dissipation circuit board. Two 25 mm × 6 mm × 1 mm thick Cu plates 14 were placed parallel to the two sides and spaced apart, and bonded on top of the insulating heat dissipation circuit board. Furthermore, three 25 mm × 6 mm × 1 mm thick Cu plates 16 were placed at a 90-degree angle to the two Cu plates 14 and spaced apart, and bonded on top of the two Cu plates 14. The size of the assembled Cu plate area is 25 mm × 25 mm. Ag paste was used for bonding.

[0099] <Preparation of Observation Samples> The resin composition was molded into the assembled Cu plate of the evaluation apparatus using a transfer molding machine under the conditions of a mold temperature of 175°C, molding pressure of 5.0 MPa, and curing time of 120 seconds, to obtain a molded product of 55 mm × 65 mm × 5.4 mmt. Next, the molded product was post-cured at 175°C for 5 hours to obtain a test piece for delamination measurement. Subsequently, the presence or absence of delamination was observed using an ultrasonic flaw detection machine (SAT). The obtained test piece was heated from room temperature (25°C) to 260°C over 800 seconds, and then cooled back to room temperature over 800 seconds. After cooling, the presence or absence of delamination was observed again using SAT, and the area of ​​delamination within the test piece was calculated. The evaluation criteria are as follows: 1: No delamination 2: Delamination area is 30% or less of the entire substrate 3: Delamination area is more than 30% but 50% or less of the entire substrate 4: Delamination area is more than 50% of the entire substrate

[0100]

[0101] Based on the above, the resin composition of this disclosure suppresses the peeling of the cured sealing portion from the substrate.

[0102] 2 Power semiconductor element 4, 12 Substrate 6 Wire 8, 18 Joint 10 Insulating layer 14 Sealing part 16 Heat dissipation member

Claims

1. A resin composition used for encapsulating power semiconductor elements in a power semiconductor module that are bonded to a heat dissipation member by sintering, comprising an epoxy resin, a maleimide compound, and a curing agent.

2. The resin composition according to claim 1, wherein the content of the maleimide compound is 30% by mass or more relative to the content of the epoxy resin.

3. The resin composition according to claim 1 or claim 2, comprising a sulfur-containing compound.

4. The resin composition according to claim 1 or claim 2, wherein the curing agent comprises a phenolic resin.

5. A power semiconductor device comprising, in this order, a power semiconductor element, an insulating substrate, and a heat dissipation member, wherein the power semiconductor element is sealed with a cured product of the resin composition described in claim 1 or claim 2, and the insulating substrate and the heat dissipation member are bonded together by sintering.

Images